It is known to machine longitudinal edges of workpieces with the aid of a circumferential milling cutter. In the prior art, the job is handled in conjunction with high cutting speeds and long chips. The cutting speed is typically substantially higher than the feed rate. Attainable practical feed rates are typically above 100 m/min and are sometimes associated with short service lives and poor economy. In various areas of application, there is a need for increasing the feed rates and improving the economy. The teeth of the known tools that are simultaneously in engagement contact the workpiece at different cutting depths and also move along cutting arcs. As a consequence, the machining surfaces have ripples, which often lead to disadvantages in terms of applications.
From Austrian Patent Disclosure AT 301989, an embodiment with a circumferential milling cutter for machining the longitudinal edges of sheet-metal bands guided between guide rollers is known. The axis of rotation of the tool is disposed perpendicular to the plane of the sheet metal. The cutting edges contact the machining surface in the same direction or the opposite direction of the feed direction, depending on the pitch circle. This creates comma-shaped chips, which in proportion to their length necessarily allow only slight spacing of the respective tooth advancement. The result is a cutting speed that is substantially higher than the feed rate. Although the demand for high working speeds sometimes exceeds the limit values of the cutting speed that are technically feasible, such objectives cannot be attained by known methods.
From German Patent Disclosure DE 3435352, a circumferential milling cutter for machining longitudinal edges is known that has spiral cutting threads. The cutting threads of the tool are at a predetermined angle to the axis of rotation. The axis of rotation is inclined, such that during the engagement, the location of the cutting edges relative to the plane of the sheet metal is perpendicular. The elliptical cutting arc of the cutting threads on the machining surface is in this way flatter than its pitch circle, and as a result long chips can be achieved. Similarly to the situation already described, the cutting speed is again substantially higher than the feed rate. However, depending on the cutting arcs, the machining surface has undulations, which under some circumstances makes it necessary to do postmachining.